What Gases are Dissolved in Natural Waters?
Water dissolves varying amounts of air which is composed of 21% oxygen, 78% nitrogen, 1% other gases (including 0.03 – 0.06% carbon dioxide). Oxygen is solublein water at room temperature and atmospheric pressure to the extent of about 9ppm. The solubility of wxygen decreases as the temperature of the water goes up, but water under presure can hold larger quantities of dissolved oxygen. Although nitrogen is dissolved in natural water it is inert gas and has little effect on the character of water used in boilers. Water doesn’t usually pick up more than 10 ppm of carbon dioxide from the air. Carbon dioxide may be dissolved in water to a much greater extent, though, through the decay of vegetation and organics in the soil. Hydrogensulphate and methane may be dissolved in some waters, but this is not a general occurrence. These gases, however, can be important when they occur as contaminants.
